Good morning. Welcome to "This week." Malaysia air mystery. Why did flight 370 vanish? This morning, breaking details on the massive search operation. The investigation into what went wrong, and those new questions about why two people boarded the flight using stolen passports. Collision-course. Putin's standoff with president Obama over Ukraine. What happens next in the war of words? And stars align, conservatives crash the capital. Our country is at a crisis point. We take it on, including our exclusive with tea party hero, Ted Cruz. Plus the powerhouse roundtable right here this Sunday morning. Hello, again, good to have you with us as we come on the air this morning, the mystery of what caused Malaysia air 370 to vanish is deepening. The frantic search for the plane continues, but no signs yet of a crash. We have late word that the pilot may have made a last-minute maneuver to turn the plane back, and there is increased scrutiny this morning of as many as four passengers on that plane, including two who boarded using stolen passports. We have team coverage from around the world including the chairman of the house intelligence committee who's been briefed on the mystery and will join us in just a moment. But lets get right to David Curley for the very latest. David. Reporter: Martha, this is the end of the second day of daylight searching, and still no sign of this Malaysian airlines 777. We need the crews to find wreckage, then they can listen to the pings of the all-important black boxes. They could solve the mystery of the sudden disappearance of this jetliner. It's every flier's greatest fear, a plane falling out of the sky without a trace. And this morning the search continues in the waters off of Vietnam for any signs of Malaysian air flight 370. 239 passengers and crew on board took off after midnight on Saturday heading for beijing. It's the red eye. But it was last heard from at the 50 minute mark. Then nothing. But no distress call or mayday signal. This morning, Malaysian officials say there is a possibility that the plane may have tried to turn back to Kuala Lumpur. We have probably over 60,000 flights every day all over the world, and that may be a conservative figure, and this sort of thing never happens. Reporter: ABC's bob woodruff is in beijing with the families waiting for answers. Ty are in the hotel where they are living these days. They told me they're praying for a miracle. Maybe they are alive. Perhaps the plane did not crash, maybe hijacked and taken away by someone to a safe place. That, of course, really does seem to be desperation. Reporter: As the search now movies near the end of the second day, questions remain. What happened during what should have been the safest part of the flight? Among the possibilities, a structural or mechanical failure. The likelihood of a structural failure in the absence of a thunderstorm is very small. Reporter: Or possible pilot error. Today's modern aircraft are so advanced, some pilots lost their basic flying skills. A dangerous situation that the FAA calls automation addiction. That was a factor in the crash of air France 447 in the atlantic in 2009. Or the most troubling scenario, a deliberate act. A bomb, hijacking or even pilot suicide. That took down Egypt air flight 990 off nantucket in 1999. Federal officials are working, law enforcement officials, the Malaysians. But aviation officials from our country also to want help. Boeing and the ntsb put together a team. They are ready to go, but they need an invitation from the Malaysians and haven't received one. Thanks very much, David. The chair of the house intelligence committee Mike Rogers joins us now with more on this mid-air mystery. There's no direct indication of terrorism. I know you have been briefed on this, what can you tell us? Yeah, the investigation is in the early stages. There's two parts, the search for the wreckage, that's incredibly important to make a determination what happened, and trying to identify the two individuals traveling on stolen passports. What can you tell us about the individuals and how that can happen? Those people who's passports were stolen actually reported that. Why weren't they stopped at the check points in an airport? Yeah. Unfortunately this I-- it's not common, but it is not unheard of, either, that stolen passports can be repurposed and used, mainly for the quality of the passports themselves. Given the right circumstances, and it clearly worked, they were able to board and gained entry. They would be doctored up, they would be individuals who would have the skillset to change those passports just enough that they could identify with the individual that was using it. They'll go back to the airport and make a determination through cameras and other means to try to identify the individuals and then track that back. So it's really very, very early. They're going through those processes now. It will be just -- it will be a matter of time. They'll probably identify them. Speaking of surveillance, the U.S. And the Pentagon has a tracking system and can see explosions in the air or missile launches. Any indication of an explosion that they may have been tracking and seeing? No. There's nothing that we've -- nothing that certainly I have seen that would indicate anything of the sort, which is adding to the mystery. The important part is they have to find some part of the wreckage in order to make those determinations. If it was mechanical or something else. Thanks very much, chairman Rogers. We'll be back to talk about the standoff in Ukraine. But for more on the mystery of Malaysia flight 370, let's bring in Pierre Thomas. And colonel Steve ganyard. He's an ABC contributor, a former marine pilot and an accident investigator during your time in the military. Start with you, Pierre. You heard about the passports, but what is happening in terms of the investigation as far as the U.S. Is involved? They're deeply concerned about those passports. Trying to get as much as information as the chairman said. The surveillance video is key. Use facial recognition technology to look at the faces and see if they can find any hits in the terrorism or criminal database. The other thing is the flight manifest is key. They're looking at the pilot. They're looking at the crew members and all the passengers. Look for any hint of something that would be untoward to suggest terrorism or something else. Right now they have no direct evidence of terrorism, but they say they cannot afford to wait. They have to look at everything possible to try to get a fix on this. Steve, you as a mishap investigator looked at all of this. The idea that the pilot turned around in flight, do you buy that? I'm still a bit skeptical. Look at the radar tape, there's a bit of a heading change. But that heading change could be that he was just going on the Normal course. We know they're way out at the edge of radar coverage. I've investigated it in the past, aircrafts disappeared without a trace, and the radar data, especially at range, is unreliable. No mayday signal. What does that tell you? If it was a catastrophic failure, mechanical, all those things that David brought up, but no mayday signal. What do you suspect here? It's hard to suspect anything with a certainty. But if something catastrophic happened and the airplane blew up, obviously there would be no mayday. But if there was a problem in the cockpit. Let's set the scene. It's at night. It's literally in the middle of the night, over the ocean, black, no horizon, auto pilot on. Things are calm. Perhaps something happened in the cockpit. Maybe a major malfunction. The first thing to do is fly the airplane. In aviation, aviate, navigate, communicate. The last thing to think about was talking about what was going on in the cockpit. If they have a problem, they'll take care of it and talk about it later. Maybe there was a period where something catastrophic was happening and they didn't have time to communicate that. I think it's extraordinary that we don't know where the airplane is. We have gps in the cars, all these things, and they cannot find the airplane. In fact the last radar contact they have, it could be way beyond that, it could be anywhere. It could be in a lot of places. There's literally tens of thousands of miles of ocean that have to be searched. Because we have a black hole with no radar data, we don't know the heading, the true altitude, the air speed, where that aircraft could go. It's going to take a lot of time. That is why? Because the radar coverage only extends off the Malaysian coast so far, and off the Vietnam coast so far. So there's a gap there. The world's a huge place, and it's not big enough to be covered by radar. If you're going to fly from Europe, you're seen. Over the north pacific, data link and satellites, but a lot of the world is not covered. Sometimes planes are out there alone and unafraid. They know where they are, they have gps, but nobody else knows it until they communicate. You have told ABC in the past and been dead on in your predictions on what brought an airplane down. This is so mysterious. Does your gut tell you anything on this one? It doesn't. We have to keep the aperture open in terms of what we consider. We wouldn't normally look at terrorism, but a plane doesn't come down or disappear at 35,000 feet. Everything has to be considered and terrorism is one of those elements. This could take a long, long time even if they find the airplane. Yep. They are saying they have to follow the evidence. The key is finding the wreckage. They are frustrated they don't have a clue in terms of physical evidence. The one thing I would add, it comes against the backdrop with the toothpaste container bombs, shoe bombs. The law enforcement and intelligence community was already keyed up, and now more so. Thanks very much, Pierre and

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